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Fri, 12 May 2023 22:09:33 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) Message-ID: <39c79d27-73ea-06a8-62fe-2b64d0fd8db5@I-love.SAKURA.ne.jp> Date: Fri, 12 May 2023 22:09:33 +0900 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:102.0) Gecko/20100101 Thunderbird/102.10.1 Subject: Re: [PATCH] debugobject: don't wake up kswapd from fill_pool() Content-Language: en-US To: Thomas Gleixner , Andrew Morton Cc: syzbot , syzkaller-bugs@googlegroups.com, Ingo Molnar , linux-kernel@vger.kernel.org, linux-mm References: <000000000000008ddb05fb5e2576@google.com> <6577e1fa-b6ee-f2be-2414-a2b51b1c5e30@I-love.SAKURA.ne.jp> <20230511204458.819f9009d2ef8b46cc163191@linux-foundation.org> <87v8gxbthf.ffs@tglx> From: Tetsuo Handa In-Reply-To: <87v8gxbthf.ffs@tglx> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 50D0710000A X-Stat-Signature: yqtkjpjja6sko4kg7b8w7ez7kq5mq67f X-HE-Tag: 1683896985-401715 X-HE-Meta: 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 6grIeyiG sLIZUtywaf2Hq/GTO4VIb+t1buD3qpUq3cqCh56IFYed2Q7iazBh8ebO9GpRsfj10rnPHE193VJYCupVndfZkLAbNQNyLWnGgR+l/m74YKcnz54FpIF0Etqj4j0h0CpCWAe5TJszSjMeBm2g9L3oLAxf2OLQBso0ta03sjfdaGFbn2+Y+u3M5Ynz2ZTlLV21RbWA0xSGo9OrItIWcUUxpNe3X+6Nfc8/0gLQwCGG9nvt/b0/GepFhCjxIzYBEG4y6bvq/qyHqiVVyhWYv+cTsRP17LSjj/0I1JjyiN9piqvAHp5DHl/d+CgJ6uMUxbfSm7ZpGOOyu5oqR2Unv2lb8ctLC2zlf2bnX2WTA9dSXockYtTVFOIaEnFbJQ9B+vavVuHTUMnSjIZ99CON+01Rx1Y+4Uw+1VClkO2banvS87Klac1B22ozHa0b824MdsMWdQBvT X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 2023/05/12 21:54, Thomas Gleixner wrote: > On Fri, May 12 2023 at 19:57, Tetsuo Handa wrote: >> On 2023/05/12 12:44, Andrew Morton wrote: >>> On Thu, 11 May 2023 22:47:32 +0900 Tetsuo Handa wrote: >>> >>>> syzbot is reporting lockdep warning in fill_pool(), for GFP_ATOMIC is >>>> (__GFP_HIGH | __GFP_KSWAPD_RECLAIM) which wakes up kswapd. >>>> Since fill_pool() might be called with arbitrary locks held, >>>> fill_pool() should not assume that holding pgdat->kswapd_wait is safe. > > https://lore.kernel.org/lkml/871qjldbes.ffs@tglx/ .config says IS_ENABLED(CONFIG_PREEMPT_RT) == false, and lockdep says about base->lock => pgdat->kswapd_wait => p->pi_lock => rq->__lock => base->lock dependency but does not say about db->lock. How can your patch fix this problem?